People doing high-end retouching often apply noise to layer masks. This is to avoid posterisation and printing errors. Especially necessary on very high or low key areas. A way to non-destructuvely add noise to masks would be appreciated.
A further option to soften this noise, which would provide the capability to non-destructively'grain' the mask.
This would all be in addition to the existng feather feature, which has its uses. At the moment you can't apply noise or even rasterise this 'feather' makes the feature less useful than it should be.